Publication WO2009077537 describes a method that is specially adapted to the inspection of tyre treads of which the tread pattern is formed by the assembly of elements having basic patterns, in reduced numbers, juxtaposed circumferentially and sequenced in a precise and determined manner.
The basic patterns of the tread pattern have similar shapes and have dimensions that are similar but not totally identical. Each type of basic pattern therefore appears several times on the circumference of the tread pattern of the casing. The choice of dimensions and the arrangement of the basic patterns are carried out in a judicious manner known to those skilled in the art for the purpose of reducing the running vibrations or noises.
The object of the method described in the publication cited above consists in comparing the reference images of only the basic patterns with the image of the real basic patterns placed on the circumference of the tyre.
It is therefore sufficient to acquire the image of the tread of a single tyre in order to obtain a sufficient collection of images of each of the basic patterns and to compute the reference images from these basic patterns by making the assumption that an anomaly is not likely to occur on all of the elements having an identical basic pattern.
Also, prior to the implementation of this method, it is necessary to identify and to locate in a precise manner the limits between the elements forming the tread pattern.